I read with much interest several of your recent comments concerning materi=
als other than the conventional (standard alloy) metal for use in the sprin=
g of a vertical. The comment about nano tubes caused me to think about how=
I will never forget the lecture given at TTU years ago by the discoverer o=
f the 'bucky ball' (Richard Smalley, Rice University Chemist). Several of =
us made bets on how long it would take for him to receive the Nobel Prize f=
or this work. He 'punctuated' the serendipitous nature of his discovery b=
y mentioning "how he expected there would have been a 'telephone ringing fr=
om heaven' had he not finally realized what 'lay before him in plain sight'=
.
How I wish that I had some samples on hand to do experiments with vari=
ous exotic materials involving nanotubes, since my guess is that they just =
"might be the ticket' to solving a lot of our problems. In the meantime, =
I would like to propose that somebody take the lead to look at possible (si=
gnificantly different) other ways to maybe improve what we've presently got=
to live with. Would it be smart, for example, to try and use torsional re=
storation as opposed to the conventional coiled spring. Yes, Lucien LacCos=
te changed the history of seismology (as a tennis player, while solving a p=
roblem given to him by his physics professor Romberg, while at UT Austin). =
He 'pulled a coil inside out' to generate a zero-length configuration that=
is much less susceptible to creep than previous springs. I have often won=
dered if any of the gravimeters he built may have also used fuzed silica (q=
uartz), since it is a much more stable material than most other types (unfo=
rtunately brittle and nonconductive).
Then Erhard came along and invented (patented) the astatic spring to give s=
imilar performance. So there may be several ways to 'skin a meso-anelastic=
cat'.
One of my ideas that was shown as a prototype at the broadband conf=
erence I would like for some of you to think about. You can find a picture=
of my "compound vertical seismometer" on the IRIS link by simply typing th=
e keywords into Google. And if you want to better understand the physics =
of how it works (benefit of period lengthening being possible by using the =
'beauty' of the eccentric in latest generation bows), you might want to rea=
d the other paper that follows, titled "Archer's compound bow, smart use of=
nonlinearity".
When I showed this prototype to some of those in attendance at the b=
roadband conference-several of them were positively impressed. They seemed=
to think of it more as a toy, however, than being practical; but I believe=
Erhard was in earnest when he mentioned that I should try to get the amate=
ur seismology community interested in doing some experiments with it.
Be apprised that it is susceptible to creep, as shown in my paper, tit=
led "creep enhanced sensitivity of seismometers", online at
http://arxiv.org/abs/physics/0508105
The approach using torsional restoration could be closer , in fact, to=
that of operating with a coil than you might think. Few people in my expe=
rience realize that the spring constant of a coil depends on the shear modu=
lus. In other words, it is the twisting of the wire of the coil that is k=
ey One of the truly impressive physics demonstrations, that shows that the=
coil actually wants (unless constrained otherwise) to wind and unwind unde=
r load change-is the Wilberforce pendulum which exhibits mesmerizing mode c=
oupling behavior.
And for those of you who want to retain the remarkable properties of f=
orce balance, there is no reason why you can't use it with this compound ve=
rtical instrument.
Also, mention was made of the possible use of single crystal silicon. I ha=
ve used reject (previous generation 3-in) wafers to great advantage in some=
of my experimental efforts. It is very easy to diamond scribe and cleave =
them into rectangular shapes. They are more elastic than one might tend to=
believe, and it may be possible to make some useful springs out of them. =
They should be much better than any metals that I know about, because a giv=
en atom is far more prone to stay where it is supposed to.
Finally, I would like to mention some work, involving springs, by the=
gentleman who changed the world of earth field measurements. Jim E. Fall=
er pioneered the free-fall method of measuring g, by counting fringes as a =
cube-corner reflector falls in a vacuum (within a vacuum) to eliminate air =
drag. Using a laser interferometric setup to generate the fringes, he impr=
oved the accuracy of the g-measurement by several orders of magnitude.
When Jim gave a seminar years ago at TTU, he also mentioned to me some=
ideas about springs that he had. Don't know whether he ever refined and p=
ublished his thoughts along the following lines.
Take four strips of elastic rectangular pieces, several times longer th=
an wide. Form a single-cycle cosine wave permanent (unstrained) shape in e=
ach of the strips. Take two of the thus formed strips and 'weld' their end=
s together to form a shape similar to the leaf spring of an old truck. Do =
the same with the other pair, and then assemble the four into a single stru=
cture having 4-fold rotational symmetry. Thus it has a stand-alone (stable=
arrangement) capability to support a load that would be placed on its top.=
Has anybody tried something like this? It should be possible to gang se=
veral of them together to increase the operational length and decrease the =
net spring constant (like springs in series).
Randall
I read with much=
interest several of your recent comments concerning materials other than t=
he conventional (standard alloy) metal for use in the spring of a vertical.=
The comment about nano tubes caused me to think about how I will nev=
er forget the lecture given at TTU years ago by the discoverer of the ̵=
6;bucky ball’ (Richard Smalley, Rice University Chemist). Sever=
al of us made bets on how long it would take for him to receive the Nobel P=
rize for this work. He ‘punctuated’ the serendipito=
us nature of his discovery by mentioning “how he expected there would=
have been a ‘telephone ringing from heaven’ had he not finally=
realized what ‘lay before him in plain sight’.
=
How I wish that I had so=
me samples on hand to do experiments with various exotic materials involvin=
g nanotubes, since my guess is that they just “might be the ticket=
217; to solving a lot of our problems. In the meantime, I would=
like to propose that somebody take the lead to look at possible (significa=
ntly different) other ways to maybe improve what we’ve presently got =
to live with. Would it be smart, for example, to try and use torsiona=
l restoration as opposed to the conventional coiled spring. Yes, Luci=
en LacCoste changed the history of seismology (as a tennis player, while so=
lving a problem given to him by his physics professor Romberg, while at UT =
Austin). He ‘pulled a coil inside out’ to generate a zero=
-length configuration that is much less susceptible to creep than previous =
springs. I have often wondered if any of the gravimeters he built may=
have also used fuzed silica (quartz), since it is a much more stable mater=
ial than most other types (unfortunately brittle and nonconductive).
Then Erhard came along and invented (patented)=
the astatic spring to give similar performance. So there may be seve=
ral ways to ‘skin a meso-anelastic cat’.
O=
ne of my ideas that was shown as a prototype at the broadband conference I =
would like for some of you to think about. You can find a picture of =
my “compound vertical seismometer” on the IRIS link by simply t=
yping the keywords into Google. And if you want to better under=
stand the physics of how it works (benefit of period lengthening being poss=
ible by using the ‘beauty’ of the eccentric in latest generatio=
n bows), you might want to read the other paper that follows, titled “=
;Archer’s compound bow, smart use of nonlinearity”.
When I s=
howed this prototype to some of those in attendance at the broadband confer=
ence—several of them were positively impressed. They seemed to =
think of it more as a toy, however, than being practical; but I believe Erh=
ard was in earnest when he mentioned that I should try to get the amateur s=
eismology community interested in doing some experiments with it.
Be apprised that it is s=
usceptible to creep, as shown in my paper, titled “creep enhanced sen=
sitivity of seismometers”, online at
http://arxiv.org/abs/ph=
ysics/0508105
&nbs=
p; The approach using torsional restoration could be closer , in fact, to t=
hat of operating with a coil than you might think. Few people in my e=
xperience realize that the spring constant of a coil depends on the shear m=
odulus. In other words, it is the twisting of the wire of the c=
oil that is key One of the truly impressive physics demonstrations, t=
hat shows that the coil actually wants (unless constrained otherwise) to wi=
nd and unwind under load change—is the Wilberforce pendulum which exh=
ibits mesmerizing mode coupling behavior.
And for those of you who want to retain th=
e remarkable properties of force balance, there is no reason why you can=
217;t use it with this compound vertical instrument.
Also, mention was made of the possible use of single crystal =
silicon. I have used reject (previous generation 3-in) wafers to grea=
t advantage in some of my experimental efforts. It is very easy to di=
amond scribe and cleave them into rectangular shapes. They are more e=
lastic than one might tend to believe, and it may be possible to make some =
useful springs out of them. They should be much better than any metal=
s that I know about, because a given atom is far more prone to stay where i=
t is supposed to.
&nbs=
p; Finally, I would like to mention some work, involving springs, by =
the gentleman who changed the world of earth field measurements. &nbs=
p;Jim E. Faller pioneered the free-fall method of measuring g, by counting =
fringes as a cube-corner reflector falls in a vacuum (within a vacuum) to e=
liminate air drag. Using a laser interferometric setup to generate th=
e fringes, he improved the accuracy of the g-measurement by several orders =
of magnitude.
&=
nbsp; When Jim gave a seminar years ago at TTU, he also mentioned to m=
e some ideas about springs that he had. Don’t know whether he e=
ver refined and published his thoughts along the following lines.
Take four strips of elastic re=
ctangular pieces, several times longer than wide. Form a single-cycle=
cosine wave permanent (unstrained) shape in each of the strips. Take=
two of the thus formed strips and ‘weld’ their ends together t=
o form a shape similar to the leaf spring of an old truck. Do the sam=
e with the other pair, and then assemble the four into a single structure h=
aving 4-fold rotational symmetry. Thus it has a stand-alone (stable a=
rrangement) capability to support a load that would be placed on its top.&n=
bsp; Has anybody tried something like this? It should be possib=
le to gang several of them together to increase the operational length and =
decrease the net spring constant (like springs in series).
&n=
bsp; Randall